Computer users employ writable and rewritable optical discs for a variety of different purposes. They may save programs or data to the discs, for archival or distribution purposes. In the case of CD-type discs, users may make music CD's that can be played in audio CD players, or save music data files to the CD's, such as MP3 files, that can be played in special-purpose CD players. For DVD-type discs, users have greater storage capacity available to them than with CD-type discs, and may be able to make video DVD's that can be played in stand-alone DVD players.
Many types of optical discs include a data side and a label side. The data side is where the data is written to, whereas the label side allows the user to label the optical disc. Unfortunately, labeling can be an unprofessional, laborious, and/or expensive process. Markers can be used to write on optical discs, but the results are decidedly unprofessional looking. Special pre-cut labels that can be printed on with inkjet or other types of printers can also be used. However, this is a laborious process: the expensive labels must be carefully aligned on the discs, and so on. Special-purpose printers that print directly on the discs can be used, but such printers are fairly expensive.
In the patent application entitled “Integrated CD/DVD Recording and Label”, filed on Oct. 11, 2001, and assigned Ser. No. 09/976,877, a solution to these difficulties is described, in which a laser is used to label optical discs. The focusing mechanism of an optical disc device including the laser usually has a feedback mechanism by which the laser's beam is focused through an objective lens, utilizing the reflectivity of the surface incident to the beam. Where the label surfaces of such optical discs have relatively low reflectivity, it would be advantageous to improve focusing of the laser beam on such surfaces, especially in situations in which the optical discs are slightly warped, which can be relatively commonplace.